Observations on Schumann Resonance in low ionosphere

Schumann Resonance (SR) is closely related with atmospheric temperature changes and electromagnetic precursors of earthquakes. In this paper, a new method to monitor SR is proposed as the heavy environment constraints in the ground-based observing. That is to transmit High Frequency (HF) electromagnetic waves into the ionosphere, where the HF signals will be cross-modulated with SR. So it can be obtained by de-modulating the HF waves. The feasibility of the experiment is verified based on the nonlinear modulation model of HF waves and SR in the lower ionosphere, in which the fair weather electric filed is taken into account. The first 4 peaks of Schumann resonance respectively at 7 Hz, 14 Hz, 20 Hz, 26 Hz are obtained in demodulation spectra of short wave timing signal BPM at the first Schumann Resonance observatory of China. The theoretical and experimental results show that it is feasible to get SR signals in the lower ionosphere from the HF demodulation spectra.